Systems and methods for controlled startup of electrical devices loading a power line

ABSTRACT

An electrical system having a plurality of devices is supplied with power by a common power supply line. One of the devices has a circuit that slows or delays device startup or activation in response to a signal indicative of power demand, draw or use by another of the plurality of devices supplied with power by the common power supply line.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/135,320,filed Jun. 29, 2011, the disclosure of which is hereby incorporatedherein by reference in its entirety.

BACKGROUND

The present application relates, in general, to power management. Inparticular, the application relates to controlling power draw byelectronic and/or electrical devices from a power line or grid.

Power usage by an electronic or electrical device (e.g., an electricalmotor, a computer, a fluorescent lamp etc.) generally varies with theoperational mode or state of the device. For example, the electrical orelectronic device (hereinafter collectively “electronic device”) mayhave a higher power demand or consumption in startup mode than duringsteady state operation. The device may exhibit a peak level of powerconsumption in the startup mode. The device may also exhibit a similarpeak level of power consumption in shutdown mode. The peak power demandplaced by the device on the power line may be significantly greater thatthe operational steady-state power demand. The power line or grid may beoverdesigned to have a supply capacity sufficient to accommodate thepeak power demand of the device (which typically may be substantiallygreater than the operational steady-state power load). However, when aplurality of devices (e.g., in industrial or household settings) arepowered by the same power line or grid, concurrent peak loading by thedevices may exceed the supply capacity of the power line of grid andlead to device and/or system failures.

Consideration is now being given to managing power demands or loadsplaced on a supply power line or grid. In particular, consideration isnow being given to solutions for controlling startup or other modes ofoperation of devices to regulate power demands placed on supply powerline or grid. Some such solutions may allow power demand/consumption bythe devices to be staggered so that the total power demand does notexceed the instantaneous supply capacity of the power line or grid.

SUMMARY

Approaches to managing power draw by a plurality ofelectrical/electronic devices coupled to a power line or grid areprovided.

In one approach, an electrical device includes a device startup oractivation circuit. A power line sensor is coupled to the device startupor activation circuit. The power line sensor is configured todynamically sense properties of a power supply line for the device. Thedevice startup or activation circuit is configured to slow or delaydevice startup or activation when the power line sensor senses a voltagedrop on the power supply line.

In another approach, an electrical system includes a plurality ofelectrical devices coupled to a power supply line. A first of theelectrical devices has a signal-generating circuit that generates asignal indicative of power demand or use by the first device. A secondof the electrical devices coupled to the power supply line includes anactivation or startup circuit, which is directly responsive to thegenerated signal indicative of power demand or use by the first device.The activation or startup circuit regulates or controls power use by thesecond device according to the signal indicative of power demand or useby the first device. The signal-generating circuit may, for example,emit a signal when the power demand or use by the first device exceeds athreshold value. In response, the activation or startup circuit mayprevent or delay startup or activation of the second device.Additionally or alternatively, the activation or startup circuit mayprevent or delay operation of the second device in a high-power modewhile the signal indicative of power demand or use by the first deviceis at or above the threshold value.

BRIEF DESCRIPTION OF THE FIGURES

In the accompanying drawings:

FIG. 1 is schematic illustration of a plurality of electrical/electronicdevices connected to a power supply line;

FIG. 2 is a block diagram illustrating components of an exemplaryelectrical device, in accordance with the principles of the solutionsdescribed herein;

FIG. 3 is a flow diagram illustrating an exemplary method for controlledstartup or activation of an electrical device connected to a powersupply line;

FIG. 4 is a schematic illustration of an exemplary electrical systemhaving controlled device-startup and activation features for anelectrical device therein, in accordance with the principles of thesolutions described herein;

FIG. 5 is a block diagram illustrating exemplary devices that can bedeployed in the electrical system of FIG. 4, in accordance with theprinciples of the solutions described herein; and,

FIG. 6 is a flow diagram illustrating an exemplary method for regulatingor controlling power use by a device in an electrical system having aplurality of electrical devices coupled to a power supply line, inaccordance with the principles of the solutions described herein;

Throughout the figures, unless otherwise stated, the same referencenumerals and characters are used to denote like features, elements,components, or portions of the illustrated embodiments.

DESCRIPTION

In the following description of exemplary embodiments, reference is madeto the accompanying drawings, which form a part hereof. It will beunderstood that embodiments described herein are exemplary, but are notmeant to be limiting. Further, it will be appreciated that the solutionsdescribed herein can be practiced or implemented by other than thedescribed embodiments. Modified embodiments or alternate embodiments maybe utilized, in the spirit and scope of the solutions described herein.

FIG. 1 shows a plurality of electrical or electronic devices (e.g.,devices 120, 130, and 140) that are supplied with power by an exemplarypower transmission line 110. Power line 110 may, for example, be adistribution line or feeder line in an electricity transmission griddelivering power to local users from a power-generating plant at aremote location. The devices may for example, be any type of electricalor electronic device. The devices may be any of a variety of industrialand/or household devices (e.g. electric motors, industrial fans, blowersand pumps, machine tools, lamps, household appliances, power tools,servers, computers, and disk drives, etc.). They may operate on directcurrent or on alternating current from a central electrical distributiongrid. A device may include active and/or passive electrical components.A device may include circuits (e.g., transformers, frequency converters,filters, etc.) that prepare or recondition power drawn from the powerline and apply it to a device component. A device may include a devicestartup or activation circuit. The device startup or activation circuitmay, for example, include an electronic or electro-mechanical powerswitch that is operable by user command or instruction. The devicestartup or activation circuit may include subcircuits for controllingoperation of various components of the device.

To manage power draw or loading of power line 110, one or more of theconnected devices (e.g., devices 120, 130, and 140) may include a powerline sensor coupled to the device startup or activation circuit. Thepower line sensor may be configured to monitor one or more properties(e.g., voltage, current, phase, frequency, noise, etc) of power line110. The device startup or activation circuit may slow or delay devicestartup in response to a property value measured by the power linesensor.

FIG. 2 shows an exemplary electrical device 210 configured according tothe principles disclosed herein. Electrical device 210 includes a devicestartup or activation circuit 220, which regulates or controls powersupply to active and/or passive electrical device components (e.g., 240a-240 d). Device startup or activation circuit 220 is coupled to a powerline sensor 230. Sensor 230 may be configured to dynamically senseproperties of a power supply line (e.g., power line 110) that isconnected to electrical device 210. Device startup or activation circuit220 may be configured to control or regulate startup or activationelectrical device 210 (e.g., by timing or regulating operation of one ormore device components 240 a-240 d) in response to sensed properties ofthe power supply line.

Sensor 230 may, for example, be configured to dynamically sense avoltage drop on the power supply line caused by transient high powerdemand by other devices (e.g., devices 130 and 140) coupled to the powersupply line. Device startup or activation circuit 220 may be configuredto slow or delay device startup or activation if the sensed voltage dropon the power supplies line occurs at or about device startup oractivation and/or about a peak power draw by device 210 from the powersupply line.

In other or additional versions, sensor 230 may be configured to sensevoltage and/or current phase on the power supply line as an indicator ofhigh power demand by other devices coupled to the power supply line.Additionally or alternatively, sensor 230 may be configured to sensehigh frequency power components on the power supply line as an indicatorof high power demand by other devices coupled to the power supply line.

Sensor 230 may be configured to sense properties of the supply powerline via of any physical or electrical connection (e.g., connection 250or 260) to the supply power line. Sensor 230 may be configured to senseproperties of the supply power line independent of any electrical supplyconnection (e.g., connection 250) to device 210. Sensor 230 may, forexample, be configured to sense properties of the supply power line viawired, wireless, inductive, or capacitive link 260 even while electricalsupply connection 250 is switched off. It will be understood that eventhough sensor 230 is referred to as ‘sensor’, it may be any suitablesensing arrangement. For example, sensor 230 may merely be a receiverwhich receives power line information derived or measured by otherexternal sensors.

In response to a sensed drop or dip in the voltage on the power line,device startup or activation circuit 220 may be configured to slow ordelay device startup or activation until the voltage on the power linerecovers to a normal line voltage value or a threshold voltage value.Device startup or activation circuit 220 may include a reference areference to the normal line voltage value or minimum threshold voltagevalue. The reference may, for example, an average power supply linevoltage value. The normal line voltage value is a power supply linevoltage value immediately before switching on the electrical device.

FIG. 3 shows an exemplary method 300 for controlled startup oractivation of an electrical device (e.g., device 120). Method 300includes dynamically sensing properties of a power supply line for thedevice (310); and, in response to a sensed voltage drop on the powersupply line at or about device startup or activation and/or about a peakpower draw by the device from the power supply line, slowing or delayingdevice startup or activation (320).

In method 300, dynamically sensing properties of a power supply line(310) may include, for example, a voltage drop caused by high powerdemand by other devices coupled to the power supply line. The propertiesof the supply power line may be sensed while a physical electricalconnection of the supply power line to the electrical device is switchedoff, for example, via other wireless or wired means. Dynamically sensingproperties of a power supply line (310) may include sensing highfrequency power components on the power supply line, and/or sensingvoltage and/or current phase as indicators of high power demand by otherdevices coupled to the power supply line.

Further in method 300, slowing or delaying device startup or activationin response to a sensed voltage drop on the power supply line mayinclude delaying device startup or activation until the voltage on thepower line recovers to a normal line voltage value or other thresholdvalue. The delay may be initiated or controlled by referencing thevoltage drop to the normal line voltage value or other threshold value(e.g., an average power supply line voltage value, power supply linevoltage value immediately before switching on the electrical device,etc.).

FIG. 4 shows an exemplary electrical system 400 having controlleddevice-startup and activation features. System 400 includes a pluralityof electrical devices (e.g., devices 420-440, 510-520) coupled to acommon power supply line (e.g., line 110). At least a first of theelectrical devices (e.g., device 510, FIG. 5) has a signal-generatingcircuit that generates a signal indicative of power demand or use by thefirst device (e.g., device 510, FIG. 5). At least a second of theelectrical devices (e.g., device 520, FIG. 5) includes an activation orstartup circuit directly responsive to the generated signal indicativeof power demand or use by the first device. The activation or startupcircuit regulates or controls power use by the second device accordingto the signal indicative of power demand or use by the first device. Theactivation or startup circuit in electrical system 400 may be configuredto allow startup or activation or a high-power operation mode of thesecond device only when the signal indicative of power demand by thefirst device has particular values (e.g., below, at or above a thresholdvalue).

FIG. 5 shows exemplary devices 510 and 520 that may be deployed inelectrical system 400. Device 510 has a signal-generating circuit 515configured to generate a signal indicative of power demand or use by thedevice. Signal-generating circuit 515 may be configured to emit anindicative signal when the power demand or use by the first deviceexceeds a threshold value, or falls below the same or another thresholdvalue. Device 520, which includes an activation or startup circuit 525,may include a signal receiver 527 or other means for receiving signalsindicative of power demand or use by other devices. Activation orstartup circuit 525 is coupled to signal receiver 527 or the othersignal receiving means. Activation or startup circuit 525 may beconfigured to prevent or delay startup, activation or high-poweroperation modes of the device while the signal indicative of powerdemand or use by another device (e.g., device 510) is at or above athreshold value.

With renewed reference to FIG. 4, the signal indicative of power demandor use by the first device (e.g., device 510) may be transmitted otherdevices (e.g., 420-440, 520) over any suitable link. The signal may bebroadcast or transmitted over electrical system 400 as an RF, ultrasonicor optical signal. Alternatively of additionally, the signal indicativeof power demand or use by the first device (e.g., device 510) may betransmitted as an electrical signal modulating power supply line 110.The first device may transmit the signal indicative of power demand oruse by the first device according to a collision avoidance protocol toavoid confusion as there may be other similarly configured devices insystem 400 that also transmit respective signals indicative of devicepower demand or use over the power supply line. The collision avoidanceprotocol may, for example, include transmission of the signal a randomtime interval after a determination that no other signal indicative ofpower demand or use by another of the electrical devices is present ordetected propagating on the power supply line. Alternatively, thecollision avoidance protocol may include transmission of the signal adevice-specific time interval after a determination that no other signalindicative of power demand or use by another of the electrical devicesis present or detected propagating on the power supply line.

In a version of electrical system 400, one or more of the plurality ofelectrical devices (e.g., devices 420-440, 510-520, etc.) may bearranged to turn-on only in assigned time windows relative to turn-on ofan initial one of the plurality of electrical devices or relative to anevent affecting power draw from power supply line 110. Alternatively oradditionally, a multiplicity of electrical devices may be arranged toturn-on in groups in a phased manner.

FIG. 6 shows an exemplary method 600 of regulating or controlling poweruse by a device according to the signal indicative of power demand oruse by another device in an electrical system having a plurality ofelectrical devices coupled to a power supply line. Method 600 includesgenerating a signal indicative of dynamic power demand or use by a firstdevice (610); and, regulating or controlling power use by a seconddevice according to the signal indicative of power demand or use by thefirst device (620).

In method 600, generating a signal indicative of dynamic power demand oruse by the first device (610) may include generating a signal bycomparing the power demand or use by the first device with respect to areference value. For example, respective indicative signals may begenerated when the power demand is at or above a first threshold valueand/or falls below a second threshold value.

Generating a signal indicative of dynamic power demand or use by thefirst device (610) may include transmitting or broadcasting anelectrical, RF, ultrasonic or optical signal. Generating a signalindicative of dynamic power demand or use by the first device (610) mayinclude transmitting the signal as an electrical signal modulating thepower supply line. The method may include transmitting the electricalsignal modulating the power supply line according to a suitablecollision avoidance protocol that is designed, for example, to avoidcollision or interference with signals indicative of dynamic powerdemand or use by other devices connected to the power supply line. Asuitable collision avoidance protocol may, for example, includetransmission of the signal a random time interval after a determinationthat no other signal indicative of power demand or use by another of theelectrical devices is detected, present or propagating on the powersupply line. Another suitable collision avoidance protocol may, forexample, include transmission of the signal a device-specific timeinterval after a determination that no other signal indicative of powerdemand or use by another of the electrical devices is detected, presentor propagating on the power supply line.

In method 600, regulating or controlling power use by the second device(620) may include limiting allowing startup or activation or ahigh-power operation mode of the second device only when the signalindicative of power demand by the first device is below a thresholdvalue. Alternatively of additionally, regulating or controlling poweruse by the second device (610) may include turning off or reducing poweruse by the second device while the signal indicative of power demand oruse by the first device is at or above a threshold value. Further,regulating or controlling power use by the second device (610) mayadditionally or alternatively include assigning one or more of theplurality of electrical devices to turn-on only in suitably selectedtime windows relative to turn-on of an initial one of the plurality ofelectrical devices or relative to an event affecting power draw from thepower supply line, and/or arranging a multiplicity of electrical devicesto turn-on in groups in a phased manner.

In the foregoing detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thesummary, detailed description, drawings, and claims are not meant to belimiting. Other embodiments may be utilized, and other changes may bemade, without departing from the spirit or scope of the subject matterpresented here. Those having skill in the art will recognize that thestate of the art has progressed to the point where there is littledistinction left between hardware and software implementations ofaspects of systems; the use of hardware or software is generally (butnot always, in that in certain contexts the choice between hardware andsoftware can become significant) a design choice representing cost vs.efficiency tradeoffs. Those having skill in the art will appreciate thatthere are various vehicles by which processes and/or systems and/orother technologies described herein can be effected (e.g., hardware,software, and/or firmware), and that the preferred vehicle will varywith the context in which the processes and/or systems and/or othertechnologies are deployed. For example, if an implementer determinesthat speed and accuracy are paramount, the implementer may opt for amainly hardware and/or firmware vehicle; alternatively, if flexibilityis paramount, the implementer may opt for a mainly softwareimplementation; or, yet again alternatively, the implementer may opt forsome combination of hardware, software, and/or firmware. Hence, thereare several possible vehicles by which the processes and/or devicesand/or other technologies described herein may be effected, none ofwhich is inherently superior to the other in that any vehicle to beutilized is a choice dependent upon the context in which the vehiclewill be deployed and the specific concerns (e.g., speed, flexibility, orpredictability) of the implementer, any of which may vary. Those skilledin the art will recognize that optical aspects of implementations willtypically employ optically-oriented hardware, software, and or firmware.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. In one embodiment,several portions of the subject matter described herein may beimplemented via Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs), digital signal processing circuits(DSPs), or other integrated formats. However, those skilled in the artwill recognize that some aspects of the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more processingcircuits (e.g., as one or more programs running on one or moremicroprocessors), as firmware, or as virtually any combination thereof,and that designing the circuitry and/or writing the code for thesoftware and or firmware would be well within the skill of one of skillin the art in light of this disclosure. In addition, those skilled inthe art will appreciate that the mechanisms of the subject matterdescribed herein are capable of being distributed as a program productin a variety of forms, and that an illustrative embodiment of thesubject matter described herein applies regardless of the particulartype of signal bearing medium used to actually carry out thedistribution. Examples of a signal bearing medium include, but are notlimited to, the following: a recordable type medium such as a floppydisk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk(DVD), a digital tape, a computer memory, etc.; and a transmission typemedium such as a digital and/or an analog communication medium (e.g., afiber optic cable, a waveguide, a wired communications link, a wirelesscommunication link, etc.). Further, those skilled in the art willrecognize that the mechanical structures disclosed are exemplarystructures and many other forms and materials may be employed inconstructing such structures.

In a general sense, those skilled in the art will recognize that thevarious embodiments described herein can be implemented, individuallyand/or collectively, by various types of electro-mechanical systemshaving a wide range of electrical components such as hardware, software,firmware, or virtually any combination thereof; and a wide range ofcomponents that may impart mechanical force or motion such as rigidbodies, spring or torsional bodies, hydraulics, and electro-magneticallyactuated devices, or virtually any combination thereof. Consequently, asused herein “electro-mechanical system” includes, but is not limited to,electrical circuitry operably coupled with a transducer (e.g., anactuator, a motor, a piezoelectric crystal, etc.), electrical circuitryhaving at least one discrete electrical circuit, electrical circuitryhaving at least one integrated circuit, electrical circuitry having atleast one application specific integrated circuit, electrical circuitryforming a general purpose computing device configured by a computerprogram (e.g., a general purpose computer configured by a computerprogram which at least partially carries out processes and/or devicesdescribed herein, or a microprocessor configured by a computer programwhich at least partially carries out processes and/or devices describedherein), electrical circuitry forming a memory device (e.g., forms ofrandom access memory), electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment), and any non-electrical analog thereto, such as optical orother analogs. Those skilled in the art will also appreciate thatexamples of electro-mechanical systems include but are not limited to avariety of consumer electronics systems, as well as other systems suchas motorized transport systems, factory automation systems, securitysystems, and communication/computing systems. Those skilled in the artwill recognize that electro-mechanical as used herein is not necessarilylimited to a system that has both electrical and mechanical actuationexcept as context may dictate otherwise.

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment). Those having skill in the art will recognize that thesubject matter described herein may be implemented in an analog ordigital fashion or some combination thereof.

Those skilled in the art will recognize that it is common within the artto implement devices and/or processes and/or systems in the fashion(s)set forth herein, and thereafter use engineering and/or businesspractices to integrate such implemented devices and/or processes and/orsystems into more comprehensive devices and/or processes and/or systems.That is, at least a portion of the devices and/or processes and/orsystems described herein can be integrated into other devices and/orprocesses and/or systems via a reasonable amount of experimentation.Those having skill in the art will recognize that examples of such otherdevices and/or processes and/or systems might include—as appropriate tocontext and application—all or part of devices and/or processes and/orsystems for generation, transmission and distribution of electricalpower, a communications system (e.g., a networked system, a telephonesystem, a Voice over IP system, wired/wireless services, etc.).

One skilled in the art will recognize that the herein describedcomponents (e.g., steps), devices, and objects and the discussionaccompanying them are used as examples for the sake of conceptualclarity and that various configuration modifications are within theskill of those in the art. Consequently, as used herein, the specificexemplars set forth and the accompanying discussion are intended to berepresentative of their more general classes. In general, use of anyspecific exemplar herein is also intended to be representative of itsclass, and the non-inclusion of such specific components (e.g., steps),devices, and objects herein should not be taken as indicating thatlimitation is desired.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations are not expressly set forth herein for sakeof clarity.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be apparent to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from the subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of the subject matter described herein.Furthermore, it is to be understood that the invention is defined by theappended claims. It will be understood by those within the art that, ingeneral, terms used herein, and especially in the appended claims (e.g.,bodies of the appended claims) are generally intended as “open” terms(e.g., the term “including” should be interpreted as “including but notlimited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood by those withinthe art that if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

The invention claimed is:
 1. An electrical system, comprising: aplurality of electrical devices coupled to a power supply line; whereinat least a first of the electrical devices has a signal-generatingcircuit that generates a signal indicative of power demand or use by thefirst device, wherein at least a second of the electrical devicesincludes an activation or startup circuit directly responsive to thegenerated signal indicative of power demand or use by the first device,wherein the activation or startup circuit regulates or controls poweruse by the second device according to the signal indicative of powerdemand or use by the first device, and wherein the activation or startupcircuit prevents or delays startup or activation or a high-poweroperation mode of the second device while the signal indicative of powerdemand or use by the first device is at or above a threshold value. 2.The electrical system of claim 1, wherein the signal-generating circuitemits a signal when the power demand or use by the first device exceedsa threshold value.
 3. The electrical system of claim 1, wherein thesignal-generating circuit emits a signal when power demand or use by thefirst device falls below a threshold value.
 4. The electrical system ofclaim 1, wherein the activation or startup circuit allows startup oractivation or a high-power operation mode of the second device only whenthe signal indicative of power demand by the first device is below athreshold value.
 5. The electrical system of claim 1, wherein theactivation or startup circuit turns off or reduces power use by thesecond device while the signal indicative of power demand or use by thefirst device is at or above a threshold value.
 6. The electrical systemof claim 1, wherein the signal indicative of power demand or use by thefirst device is broadcast as an RF, ultrasonic or optical signal.
 7. Theelectrical system of claim 1, wherein the signal indicative of powerdemand or use by the first device is transmitted as an electrical signalmodulating the power supply line.
 8. The electrical system of claim 1,wherein the first device transmits the signal indicative of power demandor use by the first device according to a collision avoidance protocol.9. The electrical system of claim 8, wherein the collision avoidanceprotocol includes transmission of the signal a random time intervalafter a determination that no other signal indicative of power demand oruse by another of the electrical devices is present or detectedpropagating on the power supply line.
 10. The electrical system of claim8, wherein the collision avoidance protocol includes transmission of thesignal a device-specific time interval after a determination that noother signal indicative of power demand or use by another of theelectrical devices is present or detected propagating on the powersupply line.
 11. The electrical system of claim 1, wherein one or moreof the plurality of electrical devices are arranged to turn-on only inassigned time windows relative to turn-on of an initial one of theplurality of electrical devices or relative to an event affecting powerdraw from the power supply line.
 12. The electrical system of claim 1,wherein a multiplicity of electrical devices are arranged to turn-on ingroups in a phased manner.
 13. A method, comprising: in an electricalsystem having a plurality of electrical devices coupled to a powersupply line, generating a signal indicative of dynamic power demand oruse by the first device, and regulating or controlling power use by thesecond device according to the signal indicative of power demand or useby the first device, wherein regulating or controlling power use by thesecond device comprises limiting power use by the second device whilethe signal indicative of power demand or use by the first device is ator above a threshold value.
 14. The method of claim 13, whereingenerating a signal indicative of dynamic power demand or use by thefirst device comprises generating a signal when the power demand or useby the first device exceeds a threshold value.
 15. The method of claim13, wherein generating a signal indicative of dynamic power demand oruse by the first device comprises generating a signal when power demandor use by the first device falls below a threshold value.
 16. The methodof claim 13, wherein regulating or controlling power use by the seconddevice comprises limiting allowing startup or activation or a high-poweroperation mode of the second device only when the signal indicative ofpower demand by the first device is below a threshold value.
 17. Themethod of claim 13, wherein regulating or controlling power use by thesecond device comprises turning off or reducing power use by the seconddevice while the signal indicative of power demand or use by the firstdevice is at or above a threshold value.
 18. The method of claim 13,wherein generating a signal indicative of dynamic power demand or use bythe first device comprises broadcasting an RF, ultrasonic or opticalsignal.
 19. The method of claim 13, wherein generating a signalindicative of dynamic power demand or use by the first device comprisestransmitting an electrical signal modulating the power supply line. 20.The method of claim 13, wherein generating a signal indicative ofdynamic power demand or use by the first device comprises transmittingthe signal indicative of power demand or use by the first deviceaccording to a collision avoidance protocol.
 21. The method of claim 20,wherein the collision avoidance protocol includes transmission of thesignal a random time interval after a determination that no other signalindicative of power demand or use by another of the electrical devicesis present or detected propagating on the power supply line.
 22. Themethod of claim 20, wherein the collision avoidance protocol includestransmission of the signal a device-specific time interval after adetermination that no other signal indicative of power demand or use byanother of the electrical devices is present or detected propagating onthe power supply line.
 23. The method of claim 13, wherein one or moreof the plurality of electrical devices are assigned to turn-on only intime windows relative to turn-on of an initial one of the plurality ofelectrical devices or relative to an event affecting power draw from thepower supply line.
 24. The method of claim 13, wherein a multiplicity ofelectrical devices are arranged to turn-on in groups in a phased manner.25. A non-transitory computer-readable medium having instructions storedthereon, the instructions forming a program executable by a processingcircuit to cause the processing circuit to perform operationscomprising: in an electrical system having a plurality of electricaldevices coupled to a power supply line, generating a signal indicativeof dynamic power demand or use by the first device; and regulating orcontrolling power use by the second device according to the signalindicative of power demand or use by the first device, includinglimiting power use by the second device while the signal indicative ofpower demand or use by the first device is at or above a thresholdvalue.
 26. The non-transitory computer-readable medium of claim 25,wherein generating a signal indicative of dynamic power demand or use bythe first device comprises generating a signal when the power demand oruse by the first device exceeds a threshold value.
 27. Thenon-transitory computer-readable medium of claim 25, wherein generatinga signal indicative of dynamic power demand or use by the first devicecomprises generating a signal when power demand or use by the firstdevice falls below a threshold value.
 28. The non-transitorycomputer-readable medium of claim 25, wherein regulating or controllingpower use by the second device comprises limiting allowing startup oractivation or a high-power operation mode of the second device only whenthe signal indicative of power demand by the first device is below athreshold value.
 29. The non-transitory computer-readable medium ofclaim 25, wherein regulating or controlling power use by the seconddevice comprises turning off or reducing power use by the second devicewhile the signal indicative of power demand or use by the first deviceis at or above a threshold value.
 30. The non-transitorycomputer-readable medium of claim 25, wherein generating a signalindicative of dynamic power demand or use by the first device comprisestransmitting the signal indicative of power demand or use by the firstdevice according to a collision avoidance protocol, and wherein thecollision avoidance protocol includes transmission of the signal arandom time interval after a determination that no other signalindicative of power demand or use by another of the electrical devicesis present or detected propagating on the power supply line.
 31. Thenon-transitory computer-readable medium of claim 25, wherein generatinga signal indicative of dynamic power demand or use by the first devicecomprises transmitting the signal indicative of power demand or use bythe first device according to a collision avoidance protocol, andwherein the collision avoidance protocol includes transmission of thesignal a device-specific time interval after a determination that noother signal indicative of power demand or use by another of theelectrical devices is present or detected propagating on the powersupply line.
 32. The non-transitory computer-readable medium of claim25, wherein one or more of the plurality of electrical devices areassigned to turn-on only in time windows relative to turn-on of aninitial one of the plurality of electrical devices or relative to anevent affecting power draw from the power supply line.